1. Field of the Invention
The present invention relates to a recording apparatus capable of recording data such as music data onto disc recording medium for example.
2. Description of the Related Art
It is known from U.S. Ser. No. 945488 filed in Sep. 10, 1992 for example that a data-rewritable disc recording medium capable of recording data such as music data by a user is provided with a so-called user table of contents (UTOC) for managing the data such as music data in a recorded area and a recordable area. When recording a program, a recording apparatus searches the UTOC for a recordable area on the disc to record audio data to the area.
It is also known that a disc recording medium such as a magneto-optical disc is far easier than a tape recording medium such as a digital audio tape (DAT) or a compact cassette tape in a random access operation.
Accordingly, one program need not be recorded always in a continuous segment. A segment herein denotes a part of one or more recording tracks in which physically continuous data is recorded. The data may be recorded in a single segment or a plurality of discrete segments. Therefore, even if tracks for recording a program are physically divided into a plurality of discrete segments, repeating a recording/reproducing operation on each segment with an associated high-speed access operation allows the program to be recorded or reproduced as an integral entity.
For example, a recording arrangement as shown in FIG. 1 is possible where a first piece of music and a second piece of music are recorded in segment T1 and segment T2 respectively that are contiguous with each other, and a fourth piece and a fifth piece are dividedly recorded in segments T4(1) through T4(4) and segments T5(1) through T5(2) respectively that are distributed over tracks. It should be noted that FIG. 1 is a schematic diagram of a recording arrangement on a disc recording medium; actually, however, a single segment often consists of a plurality of tracks formed spirally or concentrically.
Meanwhile, when recording and erasing of programs are repeated on a magneto-optical disc, the disc comes to contain both recorded segments and erased segments at the same time. When overwriting a recorded program with another shorter than it in music playing time for example, a resultant differential area becomes meaningless as integral data. So, an area recorded with such a fragmentary data is registered in the above-mentioned UTOC as a recordable area. This prevents data recording areas otherwise wasted from being formed as a result of repeating recording and erasing operations. Here, it should be noted that data to be recorded includes not only music signals but also any other digital signals, and a block of the data continuous in its content and meaningful as an entity is hereinafter referred to as a program.
It is apparent that, with the above-mentioned disc medium, recording of a program is continued by accessing a plurality of segments which provide recordable areas for parts of the program respectively and, at reproduction, the segments are accessed so that the parts are read to be put together into the original continuous program. Information necessary for linking the segments and indicating the recordable areas is stored as UTOC information which is rewritten at each rewriting or erasing operation as mentioned above. A recording/reproducing apparatus is controlled so that it reads this UTOC information to perform a head access operation for a proper recording/reproducing operation.
Meanwhile, an undue vibration or impact applied to the recording/reproducing apparatus may cause a track jump. For example, as shown in FIG. 2(a), if there are recorded areas REAs adjacent to both sides of a freely recordable area FRA, a recording head (an optical head or a magnetic head) normally scans from address A1 to address A2; however, a track jump may throw the recording head out of the FRA into the adjacent REA as indicated by a dashed line represented by TJ of FIG. 2(b). The track jump may destroy recorded data for example, a portion indicated by DS in the figure, making the data irrecoverable. Therefore, if the track jump occurs, a recording operation under way must be immediately suspended (that is, laser power output or magnetic-field application must be turned off).
A detection of a track jump is disclosed in U.S. Pat. No. 5,012,461 for example in which absolute-position information recorded on a disc as a pregroup (a wobbling group) is monitored for its continuity and a track jump is determined upon detecting a discontinuity to suspend a recording operation under way. However, the above-mentioned disclosure has a drawback in that, during a delay until information on a reflected light coming from a pregroup is decoded as the absolute-position information, a jump may have taken place over several tracks for example, making impossible the prevention of data destruction. That is, braking a scanning operation based on the absolute-position information is often too late to protect data against destruction.
In another approach, a traverse signal generated when a laser spot traverses a track is monitored to detect a track jump. This method is quick the detection. Actually, however, the traverse signal may also be generated by a foreign matter on the disc for example, indicating a false track jump. If a recording operation is suspended by the traverse signal generated by the foreign matter on the disc, recording efficiency decreases, thereby lowering practicality of an apparatus based on such a detection method. This problem is conspicuous especially when dubbing a piece of music from a source equipment unit.